In a small saucepan over medium heat, mix together the blueberries, sugar, and lemon juice. Heat until the sugar is dissolved and the blueberries are broken down, or about 5 minutes. You may need to break down the blueberries a little more with a fork. This will make about 0.75 cup of syrup.

Preheat the oven to 425°F. Line a muffin tin with paper liners.

In a medium bowl, mix together the flour, sugar, baking powder, and salt.

In a separate bowl, whisk together the melted butter, eggs, vanilla extract, and milk.

Slowly add the dry ingredients to the wet ingredients, mixing until just combined. Do not overmix.

Gently fold in the blueberries.

To make the crumble topping, mix together the flour, granulated sugar, brown sugar, lemon zest, salt, and melted butter in a small bowl.

Fill each muffin cup just about full with the batter.

Spoon about 1 tablespoon of blueberry syrup on top of each muffin.

Sprinkle about 1.5 tablespoons of the crumble topping over each muffin.

Bake for 10 minutes. After 10 minutes, reduce the oven temperature to 375°F and bake another 19-21 minutes, or until a toothpick inserted into the center of a muffin comes out with a few crumbs, but no wet batter.

Allow the muffins to cool in the tin for 10 minutes before transferring them to a wire rack to cool completely.